This type of pyroelectric infrared detection device generally comprises a circuit board and a pyroelectric sensor array mounted on the circuit board. The pyroelectric sensor array consists of a pyroelectric board and a plurality of pyroelectric sensors (pyroelectric elements) formed on the pyroelectric board. As for thus configured pyroelectric infrared detection device, infrared detection sensitivities of the pyroelectric elements might vary according to an arrangement of the pyroelectric elements.
For example, according to Patent Document 1, as compared with a heat generated by an infrared light in an infrared sensor element (pyroelectric element) arranged in the vicinity of an end of a pyroelectric board, a heat generated in an infrared sensor element arranged in the vicinity of the center of a pyroelectric board is easily dissipated (i.e. a thermal resistance tends to be lowered). Accordingly, detection sensitivities of the infrared sensor elements may vary. According to Patent Document 1, the infrared sensor element and the circuit board are connected with each other by a solder bump. It is possible to adjust the variation of the thermal resistance by forming a size of a cross-section of the solder bump in the vicinity of the end of the pyroelectric board to be different from a size of the cross-section of the solder bump in the vicinity of the center of the pyroelectric board. It is therefore possible to reduce the variation of the detection sensitivity.